The present invention relates to a needle apparatus.
Injection devices which use a sharp needle to enter human tissue are now widely recognized as being hazardous to users and other individuals because the sharp point, contaminated by its exposure to the tissue of the first person may penetrate the skin of a second person and in doing so may carry micro-organisms from the patient on whom the injection device was first used into the tissue of a second person. Such transmission may result in the development of disease in the second person. When the penetration of the skin is accidental it is referred to as xe2x80x9cneedlestick injuryxe2x80x9d or xe2x80x9cneedleprick injuryxe2x80x9d.
Disease transmission by this means is now recognised as a major cause of occupational disease transmission to healthcare workers. The prevention of such transmission has resulted in the setting up of expensive and inefficient procedures and has caused an increase in the cost of providing medical support.
Transmission of disease may also result from the deliberate re-use of a sharp need by a second person and this is a major cause of transmission of such diseases as hepatitis C and AIDS (HIV) amongst users of narcotic intravenous drugs. Many other infectious diseases may be transmitted from one person to another by contaminated needles.
Three main strategies have been put in place to reduce the risk of disease transmission by contaminated needles. These are
(i) strict adherence to methods and procedures which reduce the risk of accidental needlestick injury,
(ii) the widespread distribution of secure containers (sharps containers) into which the used needles can be placed as soon as possible after use, and
(iii) the invention and development of injection devices whereby the sharp needle point can be covered soon after use, so reducing the risk of needlestick injury, and in many examples, reducing the possibility of the injection device being used a second time.
A disadvantage of all of these strategies is that they all cause some perturbation of optimal or most efficient clinical practice and all incur increased expense in providing medical care. Often these factors mean that the safety measures fail not because the device does not provide safety but simply because they are not put into universal practice. Most importantly, these strategies and techniques may leave a xe2x80x9cwindow of riskxe2x80x9d in the interval between removing the contaminated needle from the tissue of a person and putting into effect the chosen procedure or technique to make the contaminated needle safe.
The prior art shows a great variety of methods of rendering sharp used needles safe. The prior art can be satisfactorily classified into three types which are:
(i) sheaths, in which a cover slides forward toward and over the needle and the sharp needle point after use,
(ii) needle retraction devices in which the needle is pulled back into the whole injection devicexe2x80x94such as a syringexe2x80x94until the sharp tip is enclosed and safe, this movement requiring novel and often expensive alternative fluid paths formed by sliding seals, side holes, or re-curved doublexe2x80x94pointed needles, and
(iii) needle capture devices which are similar to needle retraction but involve a detachable needle assembly linking a needle base with a syringe and a catch linking an inner part of the syringe, usually the piston or plunger, with the detachable needle assembly, so operating only after the syringe is used and emptied.
Most of these strategies can only be applied after removal of the contaminated sharp needle from the tissue of the patient and a risk of needlestick injury remains until they are applied.
It is an object of the present invention to provide a needle apparatus which can be used in much the same way as conventional tubular injection needles without requiring difficult or complex techniques to maintain fluid transfer passages during movement of the needle within the apparatus.
In accordance with one aspect of the present invention there is provided a needle apparatus comprising a thin walled catheter having a free end closely enclosing a tubular needle having a sharp point, characterised in that the needle and/or the catheter is mounted to a housing and the needle and the catheter are longitudinally moveable relative to one another between a first position at which the needle extends from the catheter a short distance and a second position at which the sharp point is located within the catheter adjacent the free end thereof, the needle remaining in a fluid pathway of the needle apparatus at all times, means being provided for positively retaining the needle and the catheter in the first position, the means for positively retaining the needle and the catheter in the first position including a manually operable catch member which upon release enables the needle and the catheter to move relatively to the second position, means being provided for moving the needle relative to the catheter to the second position upon release of the catch member, and the needle apparatus being arranged to pierce tissue when the catheter and the needle are in the first position.
In accordance with a further aspect of the present invention there is provided a needle apparatus comprising a thin walled catheter having a free end closely enclosing a tubular needle having a sharp point, characterised in that the needle and the catheter are longitudinally moveable relative to one another between a first position at which the needle extends from the catheter a short distance and a second position at which the sharp point is located within the catheter adjacent the free end thereof, the needle remaining in the fluid pathway of the needle apparatus at all times, means being provided for positively retaining the needle and the catheter in the first position including a catch member which upon release enables the needle and the catheter to move to the second position, the needle apparatus being arranged to pierce tissue when the catheter and the needle are in the first position, wherein the needle has a rearward end containing an aperture and having a further sharp point arranged to pierce a barrier member in the housing when the catheter and the needle move to the second position so as to establish fluid communication with a chamber which contains or is arranged to contain fluid.
In accordance with a yet further aspect of the present invention there is provided a needle apparatus comprising a thin walled catheter having a free end closely enclosing a tubular needle having a sharp point, characterised in that the needle and the catheter are longitudinally moveable relative to one another between a first position at which the needle extends from the catheter a short distance and a second position at which the sharp point is located within the catheter adjacent the free end thereof, the needle remaining in the fluid pathway of the needle apparatus at all times, means being provided for positively retaining the needle and the catheter in the first position including a catch member which upon release enables the needle and the catheter to move to the second position, the needle apparatus being arranged to pierce tissue when the catheter and the needle are in the first position, means being provided for positively retaining the needle and the catheter in the first position wherein the apparatus includes a housing having a flexible wall portion which upon a change in internal pressure of the housing moves laterally to act as the catch member to enable the catheter and the needle to move to the second position.